Just a basic render loop that uses Go + SDL + OpenGL

sdl_opengl.go

package main

import (
	"github.com/banthar/Go-SDL/sdl"
	"github.com/banthar/gl"
)

type Game struct {
	Surface *sdl.Surface
	Quit	bool
}

var game = &Game{}

func Init() {
	if sdl.Init(sdl.INIT_EVERYTHING) != 0 {
		panic("Unable to start SDL")
	}
	
	ConfigureGL()
	
	game.Surface = sdl.SetVideoMode(640, 480, 32, sdl.HWSURFACE | sdl.GL_DOUBLEBUFFER | sdl.OPENGL)
	if game.Surface == nil {
		panic("Unable to init surface")
	}
	
	InitGL()
}

func ConfigureGL() {
	// http://www.sdltutorials.com/sdl-opengl-tutorial-basics	
	sdl.GL_SetAttribute(sdl.GL_RED_SIZE,        8)
	sdl.GL_SetAttribute(sdl.GL_GREEN_SIZE,      8)
	sdl.GL_SetAttribute(sdl.GL_BLUE_SIZE,       8)
	sdl.GL_SetAttribute(sdl.GL_ALPHA_SIZE,      8)

	sdl.GL_SetAttribute(sdl.GL_DEPTH_SIZE,      16)
	sdl.GL_SetAttribute(sdl.GL_BUFFER_SIZE,        32)

	sdl.GL_SetAttribute(sdl.GL_ACCUM_RED_SIZE,    8)
	sdl.GL_SetAttribute(sdl.GL_ACCUM_GREEN_SIZE,    8)
	sdl.GL_SetAttribute(sdl.GL_ACCUM_BLUE_SIZE,    8)
	sdl.GL_SetAttribute(sdl.GL_ACCUM_ALPHA_SIZE,    8)

	sdl.GL_SetAttribute(sdl.GL_MULTISAMPLEBUFFERS,  1)
	sdl.GL_SetAttribute(sdl.GL_MULTISAMPLESAMPLES,  2)

	/*
These are all basic memory sizes for how much data OpenGL will store (except sdl.GL_MULTISAMPLEBUFFERS/sdl.GL_MULTISAMPLESAMPLES, those are for something else). By increasing these, you will effectively increase how much memory OpenGL will use for color information, and the buffer. As I mentioned before, the default on all of these is usually just fine. If you wish to set these, the values I have up above are pretty good. Be sure to call sdl.GL_SetAttribute before calling sdl.SetVideoMode. One thing I want to mention is on sdl.GL_MULTISAMPLEBUFFERS. This is basically your anti-aliasing flag. By turning this on, you are turning on anti-aliasing. sdl.GL_MULTISAMPLESAMPLES is how much to anti-alias. A value of 2 is pretty standard if turned on, 4 is also commonly used. Just keep in mind that this can be resource intensive for some systems. Also, not every computer is able to perform anti-aliasing. And one last note! Make sure your sdl.GL_DEPTH_SIZE is a power of two (16, 32 works), otherwise anti-aliasing may not work for you.
	*/
}

func InitGL() {
	gl.ClearColor(0, 0, 0, 0)
	gl.ClearDepth(1.0)
	gl.Viewport(0, 0, 640, 480)
	gl.MatrixMode(gl.PROJECTION)
	gl.LoadIdentity()
	gl.Ortho(0, 640, 480, 0, 1, -1)
	gl.MatrixMode(gl.MODELVIEW)
	gl.Enable(gl.TEXTURE_2D);
	gl.LoadIdentity()
}

func Quit() {
}

func Event() {
	for e := sdl.PollEvent(); e != nil; e = sdl.PollEvent() {
		switch e.(type) {
			case *sdl.QuitEvent:
				game.Quit = true
			default:
		}
	}
}

func Draw() {
	gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
    gl.LoadIdentity()
 
    gl.Begin(gl.QUADS)
    
    gl.Color3f(1, 0, 0)
    gl.Vertex3f(0, 0, 0)
    
    gl.Color3f(1, 1, 0)
    gl.Vertex3f(100, 0, 0)
    
    gl.Color3f(1, 0, 1)
    gl.Vertex3f(100, 100, 0)
    
    gl.Color3f(1, 1, 1)
    gl.Vertex3f(0, 100, 0)
        
    gl.End()
 
    sdl.GL_SwapBuffers()
}

func main() {
	Init()
	
	defer Quit()
	
	for !game.Quit {
		Event()
		Draw()
	}
}